Small Boat Forum

homemade outboard

Think I might have a running prototype here, its not pretty or perfect but the prop spins in the water so what the heck. Using the grinder then a file on the spinning shaft worked great, i was worried about how to turn trim down that shaft and I was relieved that that method you suggested worked. Threading was no problem expect that I had to put the bit in the vice grip instead of using the turning mechanism that i bought because the bit did not fit inside. After I made the threads, i decided the cut the shaft length down about 8", so I reground and re-threaded it. I found that putting the prop on the shaft and using a nut in front to tighten it provided enough friction for the prop to turn withought having to drill thru the shaft and use a cotter pin or similar. You probably noticed the larva-like thing in the photos-that was a fiberglass cover that I made for the lower end. I sealed it up with caulk as well as any other holes I could find. When I dipped the lower end in water, it flooded eventually. I could not find an obvious leak anywhere so I gave up on that and just enclosed the whole lower end in garbage bags and duct tape, did the trick although not the look I wanted. Finally did the garbage can test today, I was really happy to see that the motor was able to turn the prop without stalling out. It did start while the prop was underwater, but only if I use a fresh battery for the drill. I first ran it at full throttle and it emptied the garbage can in like 3 seconds. I filled the can back up and ran it at the lowest throttle I could get without the motor stalling and watched it churn the water for about 15 minutes. It was great, I am so glad this thing held together. The belt got wet from splashing water but it did not seem to slip, it just threw the water straight up and to the side. I am going to leave it sitting in water overnight to see if it leaks, especially at the stuffing box. I also looked at a boat today, a 14" alum with a 9.9 hp outboard for $1200. It looked ok for this application but I thought it was a bit pricey. I will keep looking, hopefully find just a boat w/o motor but with ores(spelling?). I think the question now is if this thing will stand up to a several hour endurance test and if it will fit on the boat. The distance between the c-clamps and the lower end pipe upper surface is 15.5"-at least visually it looks like its going to be tight. Update photos below as well as a movie that came out kind of dark.http://machnumber2.50megs.com/photos/outboard2/photos/outboard.htmlhttp://machnumber2.50megs.com/photos/outboard2/photos/movie/MVC-846V.MPG

Looks like you have made some good progress, I am not surprized that the nut by itself is strong enough to hold the prop. But I will point out something here. thing 1. You definitly need a way to lock the nut from comming off the shaft. drilling a hole and using a cotter pin is the most accepted way. Props have been known to spin off. Using the nut to actualy grip the prop to the shaft is not a good thing, The nut is just suposed to compress the prop into its seat. ( the pin I mentioned ) letting the pin do the work of turning it, not the nut. Fora few hours use, I would say your current method is fine, But for something built for regulare use, I would strongly suggest a little more time and attention to the prop connection.

About the fiberglass cast. I was only sugesting you cover the area of the hole you cut in the bottom, It seams you covered the whole lower end with fiberglass. I am more then just a bit confused with what happened and why. I have never had fiberglass leak as you discribed. All the ABS joints should be sealed with silicone, leaving only the stuffing box and the access hole to leak. Ow,,BTW, I dont know how true it is, by my father says all stuffing boxes leak to some degree.Its part of there design. Using the piece you cut out and a 8 inch or so piece of mesh cloth with a little resin should seal that access hole up no problems. from your discription, it seams you actualy had holes, or leaks through your mesh fiberglass cast thing. This should not be. It may reguire a second coat of resin to seal it all up, However , like I said, You seam to be covering much more area then I had envisioned. That abs should be watertight to start with, so there should be no need to cover so much of it.

Looking at a boat now are we..1200 does seem a bit pricey, but not that pricey for the boat I saw in the pictures.It isnt the steal I got, but it isnt that bad. If you dont want the motor, you can probably sell it to recoop some of your cost. ( or even keep is as a stanbye in case of mecanical failure ) I do not know teh going rate for john boats in Ca, but around here, just a boat around 14 foot or so is buyable for 4 too 500 on a trailor usualy. I shoped for months before I found teh steel I got, SO I wish you luck in your boat hunting.

The 15 inches you have will qualify that as a short shaft. SHouldnt be too much of a problem finding a boat to mate that too.

I sure hope you plan on installing a manual pull start to that bad boy. relying on a fresh batterie pack in your drill could be a downfall out on the water.

Guess thats about it for this installment of "the Back yard Outboard home prodject mechanic " catch up with you laters.

dang it the lower end flooded again, even with the garbage bags wrapped around. I figure its going to be a tear in the bags, or leak at the stuffing box or leaking where i had put a hole in the g-bags to allow the shaft to pass thru then tried to tape it shut on the pvc pipe around the shaft. I read that stuffing boxes are supposed to leak, but only one to two drops per minute while running-if tightened properly. since I am missing the jam nut and I have no idea how tight is enough, i might crank it down some more and put a hose clamp or something on it to hold it in place if it is spinning loose. At first I intended to fiberglass in the hole at the bottom of the lower end, but then I thought that that hole gave me access to almost everthing there so I wanted to make an access panel instead of a permanent cover. The bump at the bottom of the fglass panel is supposed to be sort of a bilge area so that the water can collect-that was the theory anyways. I thought I could make a cover with fiberglass that could simply be removed when I needed to work on it. I put a gargabe bag on the lower end then fiberglassed on top of that (3-layers) so I could remove the cover once it dried. This did not work that well, the garbage bag wrinkles so that the cover does not fit snugly. I put the dried cover back on, drilled a bunch of holes along the perimeter and put in machine screws to hold it in place (after caulking it) Its difficult to tell ifs its water tight-the problem is that I cant see in there to see where the leak is coming from. I want to avoid drilling the shaft for the cotter pin if I can-for me it would be alot of work and trial and errors till I got it to go together correctly. The shaft spins opposite to the nut turning off. I might try to double up the nuts in front of the prop with a lockwasher in-between. By the way the reason I start the motor with the drill is that I broke the manual start when I first got the motor, i discovered by accident that a socket head that I had fit perfectly on the flywheel ratchet. Sure makes it easier to start. Its a dedate if I want to fix the manual start- even if I fix it, I will have to stand up in the boat and pull upward on the pull start, kind of awkward. I have 2 additional batteries that fit the drill and will charge em all up before a trip if I have to. Once the motor is hot its starts pretty easy even with the prop in the water. That reminds me, remember you said the noise would be better if I piped the exhaust underwater-what a difference! much quieter. I first soldered copper pipe together. It melted and fell apart in less than a minute, I reassembled it and then held it together with machine screws. The question now is the routing of the pipe to the water. Going to head to boattrader.com to see what they have. No updated photos.

Hmm,, well as I am sure you have discovered,, A removable access pannle with fiberglass like that aint gonna work, The only way you gonna get back into that once sealed is with a hammer ;p The biggest drawback to using the ABS or even PVC. However,, You are where you are and must move forward from there.. If you want to know where your leaks are, just fill it with water outside of the barrel, and watch for where the water runs. I am betting on near the stuffing box myself. I would have tried to talk you out of the cast Idea were I around. If you were insistant on a accessable access panle, I probably would have tried to direct you to what can only be called, a "Rubber ace bandage" and a few hose clamps. ( car sized tube) the only other place water should come in is your beering mount bolts or the more oviouse access pan..From what I saw in the pictures, the bearing bolt did not look like it had enough, if any silicone around it .One other thing comes to mind,, I really dont like the plastic cap the stuffing box comes through, I think you would be better off cutting a round plywood plug for that and sealing that in place. My concern is the plastic hole will become oblong through use, and will most definitly leak.

remember, I build for keeps, My repairs are often the new strongest part of whatever the unit is

Using 2 nuts and a lock washer will work. I wish I could convince you to do it right and drill that puppy, But I wont keep after you about it ;p 2 nuts will work. My real problem with the hole thing really isnt prop spin off, although that is a real danger, my problem is that you are using friction preshure to "grip" and "rotate" the prop. Every single aoutboard I ever saw, did not rely on the grip of the nut to rotate the prop. That is something they use in making house fans. I am sure it will work as is, for awile.. The force pressing against the prop holding it in place is a constant. the forces trying to make the prop spin on the shaft are constant, every varying and sometimes increadably strong and will eventualy make the prop spin on the shaft in time unles you use some form of shear pin behind it. Ok,, I wontmention it again unles you ask hehe,

I am very sure it is much quieter with the exshaust piped underwater. Night and day even hehe.. Too bad you live way over there, Im looking at a 14 foot aluminume boat, with trailor and 4 hp motor for 500 bucks in our local buy it sell it swap it ragazine. Also having a few batteries for your drill I guess is suficient back up.. Might concider removing the pull start housing and rigging it so you could rap a rope around it old fashioned style if you had too. It isnt ENtirely unreasonable that the drill itself might fail, or be droped overboard. I supose a lanyard on it could prevent loss overboard.. Anyway.. a friend just called, we are going to take the motercycles for a ride,, Ill catch you later

havent worked on the project since the last post, been mostly concentrating on getting a boat. By the way your idea of filling the inside lower end with water is the most awesome idea, I was like "duh" why am I wrapping in garbage bags jeez. I will do that as soon as I get back to it. I am bidding a a boat, its sort of a hybrid inflatable-figerglass hull type thing. It comes with a 30 hp outboard that looks to be in good shape. take a look at the link and let me know what you think... http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2410418053

Well, that semi inflatable dosent look to bad. I am not sure I would pay that much for a inflatable ( almost 1500 now ) but then again, the motor itself is just about worth that alone so it ia probably a pretty good buy.Good Luck with the bidding.

Well I won the boat, $1775 on ebay. Way way way more than I wanted to spend, but I did comparables on it and it seems to be worth about that in this area. No work on the project yet. Ken did you get the carb and shaft problem figured out?

Tested the boat today. It worked great I am very happy with it. My wife and I sat next to eachother in the front, I was suprised by how much space it had, we were comfy. The motor started right up and it was very powerful when I opened it up. I would say this thing tops off at about 40+ mph. Unfortuanately I do not think I will be able to test the homemade outboard on this boat, I will have to move the existing motor and dont want to mess with it. It was a fun project though. Photos below http://machnumber2.50megs.com/photos/boat2/boat2.html

I looked at the rear and it does not look like there will be enough room for both motors. I can try to make the two square steel motor mount plates smaller then see if that helps. Or if it is easier, just take off the 30 hp motor and hook up the prototype.

That will kinda suck if you have to remove the 30 to test the prototype. But then again, it isnt that big of a deal unmounting the 30. I can see it now, You will use it once, prove to yourself it works, take a few pictures, then remount the 30 and never look back hehehe.

That will probably happen, not the way I envisioned it orgiginally. Just a thought, if I sent this thing to you, would you be interested in using/testing it, maybe making improvements? Its really a heap of bad welding and leaking lower end but I am curious if it would work.

Wonder what the shipping cost on that would be from California to Maine.

If you shiped it up I can test it, and maybe make a modification or 2. I am pretty certain it will work. From what I understand, the only real hurdle left is stopping the lower unit from leaking. Hmm, well, that and the starter rope,, I dont have a cordless drill anymore.

Personaly, I have been Eyeing this weed eater I got from the rubish heap the other day. Its either gonna become a 12 volt generator, or a outboard for my friends raft.

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